Linalool


Linalool refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. These have multiple commercial applications, the majority of which are based on its pleasant scent. It has other names such as β-linalool, alcohol, linaloyl oxide, allo-ocimenol, and 3,7-dimethyl-1,6-octadien-3-ol.

Nature

Over 200 species of plants produce linalool, mainly from the families Lamiaceae, Lauraceae, and Rutaceae, but also birch trees and other plants, from tropical to boreal climate zones, including fungi.

Enantiomers

Linalool has a stereogenic center at C3 and therefore there are two stereoisomers: --linalool is also known as licareol and --linalool is also known as coriandrol.
Both enantiomeric forms are found in nature: -linalool is found, for example, as a major constituent of the essential oils of coriander, cymbopogon, and sweet orange flowers. -linalool is present in lavender, bay laurel, and sweet basil, among others.
Each enantiomer evokes different neural responses in humans, so are classified as possessing distinct scents. --Linalool is perceived as sweet, floral, petitgrain-like and the -form as more woody and lavender-like.

Biosynthesis

In higher plants, linalool, is an acyclic monoterpenoid. Like the majority of monoterpenes, it starts at the condensation of dimethylallyl diphosphate and isopentenyl diphosphate to form geranyl pyrophosphate. With the aid of linalool synthase, water attacks to form the chiral center.LIS appears to show a limonene synthase-type catalysis through a simplified "metal-cofactor-binding domain of the residues involved in substrate...binding in the C-terminal part of the protein" suggesting stereoselectivity and the reasoning behind why some plants have varying levels of each enantiomer.
pathway. Abbreviations used: geranyl diphosphate synthase, pyrophosphate ester, isopentenyl pyrophosphate, dimethylallyl pyrophosphate, geranyl pyrophosphate. Stereogenic centers are indicated by an asterisk.|654x654px

Uses

Linalool is used as a scent in 60% to 80% of perfumed hygiene products and cleaning agents including soaps, detergents, shampoos, and lotions.
It is also used as a chemical intermediate. One common downstream product of linalool is vitamin E.
In addition, linalool is used by pest professionals as a flea, fruit fly, and cockroach insecticide. It can also be used as a method of pest control for codling moths. Linalool creates a synergistic effect with the codling moth's pheromone called codlemone, which increases attraction of males.
Linalool is used in some mosquito-repellent products; however, the EPA notes that "a preliminary screen of labels for products containing inalool indicates that efficacy data on file with the Agency may not support certain claims to repel mosquitos."

Plants that contain linalool

Linalool can be absorbed by inhalation of its aerosol and by oral intake or skin absorption, potentially causing irritation, pain and allergic reactions. Some 7% of people undergoing patch testing in Europe were found to be allergic to the oxidized form of linalool.